Undulating Terrain Outdoor Run — 90-Minute Aerobic Endurance Session

Session Overview

This 90-minute outdoor run builds aerobic endurance while exposing your legs to the rolling hills and mixed gradients you will encounter on most UK triathlon run courses. Varied terrain forces your muscles to adapt to both uphill power production and downhill eccentric loading, improving overall run durability and reducing injury risk on technical courses. Use this as your long run session for the week in an intermediate training block.

What You’ll Need

• Route with 150–300m total elevation gain (plan with Strava Route Builder or Komoot)
• Running shoes suitable for mixed surfaces (road shoes fine for tarmac hills)
• GPS watch to track pace, heart rate, and elevation profile
• Handheld bottle or lightweight running vest for runs over 75 minutes
• One gel or 30g of carbohydrates for the 45-minute fuel point (optional for shorter efforts)

Warm-Up (10 minutes)

Begin the first 10 minutes on flat ground at a fully conversational easy pace (RPE 3–4). Your joints, tendons, and connective tissue need this gradual build before you introduce climbing demands. Do not start ascending until your body feels genuinely warm and your stride has settled.

Main Set

Run for 70 minutes across undulating terrain at Zone 2–3 effort (RPE 5–6.5). Your chosen route should include multiple shorter climbs of 30–90 seconds each with matching descents. Use the following intensity cues for each section:

• Uphills: Shorten stride, increase cadence slightly, lean from the ankles. Keep effort consistent — use perceived exertion not pace. Walk for 10–20 seconds on very steep sections to stay aerobic.
• Flat sections: Return to your comfortable Zone 2 pace. These are active recovery sections within the run.
• Downhills: Mid-foot strike, relaxed arms, let gravity assist without braking aggressively. Build to a moderate tempo on gentler descents; stay controlled on steep drops.
• Nutrition at 45 minutes: Take on a gel or 30g of carbohydrates here if you have not eaten in the preceding 2–3 hours, particularly on runs where you will push tempo in the final 20 minutes.

Cool-Down (10 minutes)

Walk for 5 minutes after finishing and then complete a standing stretch routine — calf raises into calf stretches, hip flexor stretch (30 seconds each side), standing quad pull, and seated hamstring reach. If your calves feel tight after descents, use a foam roller that evening and elevate your legs for 10 minutes post-session.

Coaching Notes

• Guide intensity by effort or heart rate on hills, not pace — your pace will naturally slow on ascents regardless of fitness, so chasing pace targets on hills is counterproductive and demoralising.
• Prioritise a smooth, relaxed stride on descents — downhill running causes significant eccentric muscle damage if you brake too hard, which accumulates as fatigue over a long season.
• Scale down: reduce to 60 minutes and choose a route with under 100m of elevation gain for beginners or mid-week recovery long runs.
• Scale up: add 4 × 15-second explosive hill sprints in the final 20 minutes of the run for a neuromuscular stimulus on top of the aerobic base work.